VOGONS


First post, by psaez

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Can a broken graphics card make the system go crazy?

I thought I break my motherboard (https://theretroweb.com/motherboards/s/dfi-ca64-tc ) after changing capacitors on it, because I have these sypmthomps:

First it boots correctly, after some minutes:

- crackling sounds on speaker
- CD constantly making startup noise
- black screen

After that, it does the same but in seconds after start instead of minutes. If it waits shut down for some time, then it takes again some minutes to start with the problems.

Then, one friend, ask me to try it with another graphics card, because I also replaced a capacitor on that gforce 4 mx 440... and for the moment, it is working with an nvidia 5200 agp with no problems (still need to test with hard drives, tualatin etc.. but doesn't have the components at this place)

I just can't understand how a graphics card can cause that.

Maybe it is not possible and simply the motherboard is working again by a miracle and will suddenly fail in some hours/days?

Reply 1 of 5, by rasz_pl

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no need for new topic, should continue in old one

Hard to tell whats going on without oscilloscope, are new caps on graphic card soldered with correct polarity? 😀 bad polarity/malfunctioning power circuit can cause graphic card to spew noise into main power lines, crackling sound from speaker is deffo in line with very noisy 5V line

https://github.com/raszpl/FIC-486-GAC-2-Cache-Module for AT&T Globalyst
https://github.com/raszpl/386RC-16 memory board
https://github.com/raszpl/440BX Reference Design adapted to Kicad
https://github.com/raszpl/Zenith_ZBIOS MFM-300 Monitor

Reply 2 of 5, by psaez

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rasz_pl wrote on 2024-04-06, 08:05:

no need for new topic, should continue in old one

Hard to tell whats going on without oscilloscope, are new caps on graphic card soldered with correct polarity? 😀 bad polarity/malfunctioning power circuit can cause graphic card to spew noise into main power lines, crackling sound from speaker is deffo in line with very noisy 5V line

sorry i thought was better to talk about graphic card in another post

the polarity is correct on the capacitor, maybe there is a way to test the new capacitor status that it is possible for a newbie like me that only haves a multimeter and a zero electronic knowledge?

Reply 3 of 5, by rasz_pl

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no, you would need ESR meter, those used to be $5 but recently are >$20, makes zero sense buying one just to test few caps once.
Post picture of the card and those replaced caps

https://github.com/raszpl/FIC-486-GAC-2-Cache-Module for AT&T Globalyst
https://github.com/raszpl/386RC-16 memory board
https://github.com/raszpl/440BX Reference Design adapted to Kicad
https://github.com/raszpl/Zenith_ZBIOS MFM-300 Monitor

Reply 4 of 5, by psaez

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rasz_pl wrote on 2024-04-06, 08:30:

no, you would need ESR meter, those used to be $5 but recently are >$20, makes zero sense buying one just to test few caps once.
Post picture of the card and those replaced caps

well finally, I removed the capacitor and I welded it again with tin, but now with my experiencie probably I did better, because now it's working!

Reply 5 of 5, by momaka

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Helps to know what power supply you are using. Cheapo power supplies can also have bad caps or be build inadequately.

And indeed post some pictures of your recapped hardware, if possible. What brand of capacitors (and series) you used for the replacement is rather important. "no-name" junk caps may not fix all of the issues or become faulty themselves after a while (typically a few days to a few years of use, depending on how cheap they are.)